<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>伪类选择器</title>
    <style>
      /* link 选中未访问过的a标签 */
      a:link {
        color:orange;
      }
      /*已经访问过的a标签*/
      a:visited {
        color: skyblue;
      }
    </style>
</head>
<body>
  <a href="https://www.baidu.com">去百度</a>
  <a href="https://www.jd.com">去京东</a>
</body>
</html>